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Resolved Magnetic-Field Structure and Variability Near the Event Horizon of Sagittarius A*
Michael D. Johnson, Vincent L. Fish, Sheperd S. Doeleman +45
Near a black hole, differential rotation of a magnetized accretion disk is thought to produce an instability that amplifies weak magnetic fields, driving accretion and outflow. The…
Levitating atmospheres of Eddington-luminosity neutron stars
Maciek Wielgus, Aleksander Sadowski, Wlodek Kluzniak +2
We construct models of static, spherically symmetric shells supported by the radiation flux of a luminous neutron star in the Schwarzschild metric. The atmospheres are disconnected…
X-Ray Polarimetry with the Polarization Spectroscopic Telescope Array (PolSTAR)
Henric S. Krawczynski, Daniel Stern, Fiona A. Harrison +49
This paper describes the Polarization Spectroscopic Telescope Array (PolSTAR), a mission proposed to NASA's 2014 Small Explorer (SMEX) announcement of opportunity. PolSTAR measures…
HEROIC: 3D General Relativistic Radiative Postprocessor with Comptonization for Black Hole Accretion Discs
Ramesh Narayan, Yucong Zhu, Dimitrios Psaltis +1
We describe HEROIC, an upgraded version of the relativistic radiative post-processor code HERO described in a previous paper, but which now Includes Comptonization. HEROIC models C…
The slimming effect of advection on black-hole accretion flows
J. -P. Lasota, R. S. S. Vieira, A. Sadowski +2
At super-Eddington rates accretion flows onto black holes have been described as slim (aspect ratio ) or thick (H/R >1) discs, also known as tori or (Polish) doughn…
Energy flows in thick accretion disks and their consequences for black hole feedback
Aleksander Sadowski, Jean-Pierre Lasota, Marek A. Abramowicz +1
We study energy flows in geometrically thick accretion discs, both optically thick and thin, using general relativistic, three-dimensional simulations of black hole accretion flows…
Three-dimensional simulations of super-critical black hole accretion disks --- luminosities, photon trapping and variability
Aleksander Sadowski, Ramesh Narayan
We present a set of four three-dimensional, general relativistic, radiation MHD simulations of black hole accretion at super-critical mass accretion rates, $\dot{M} > \dot{M}_{\rm…
Photon-conserving Comptonization in simulations of accretion disks around black holes
Aleksander Sadowski, Ramesh Narayan
We introduce a new method for treating Comptonization in computational fluid dynamics. By construction, this method conserves the number of photons. Whereas the traditional "blackb…
HERO: A 3D General Relativistic Radiative Postprocessor for Accretion Discs around Black Holes
Yucong Zhu, Ramesh Narayan, Aleksander Sadowski +1
HERO (Hybrid Evaluator for Radiative Objects) is a 3D general relativistic radiative transfer code which has been tailored to the problem of analyzing radiation from simulations of…
Fast Variability and mm/IR flares in GRMHD Models of Sgr A* from Strong-Field Gravitational Lensing
Chi-kwan Chan, Dimitrios Psaltis, Feryal Ozel +4
We explore the variability properties of long, high cadence GRMHD simulations across the electromagnetic spectrum using an efficient, GPU-based radiative transfer algorithm. We foc…
Stable, levitating, optically thin atmospheres of Eddington-luminosity neutron stars
M. Wielgus, W. Kluźniak, A. Sądowski +2
In general relativity static gaseous atmospheres may be in hydrostatic balance in the absence of a supporting stellar surface, provided that the luminosity is close to the Eddingto…
The Event Horizon of M87
Avery E. Broderick, Ramesh Narayan, John Kormendy +3
The 6 billion solar mass supermassive black hole at the center of the giant elliptical galaxy M87 powers a relativistic jet. Observations at millimeter wavelengths with the Event H…
Powerful radiative jets in super-critical accretion disks around non-spinning black holes
Aleksander Sadowski, Ramesh Narayan
We describe a set of simulations of super-critical accretion onto a non-rotating supermassive BH. The accretion flow is radiation pressure dominated and takes the form of a geometr…
Numerical Simulation of Hot Accretion Flows (III): Revisiting wind properties using trajectory approach
Feng Yuan, Zhaoming Gan, Ramesh Narayan +3
Previous MHD simulations have shown that wind must exist in black hole hot accretion flows. In this paper, we continue our study by investigating the detailed properties of wind, s…